A common use of seals is to prevent fluids from leaking around shafts in aircraft gearboxes, aircraft accessories, pumps, motors, turbines, spindles, and other rotating equipment. Typically, mechanical face seals or lip seals are used to seal such shafts, but there are distinct disadvantages to both types of seals. Mechanical face seals operate at higher speeds and pressures and seal life is far superior to that of existing lip seals. However, mechanical face seals are normally three times axially longer than a lip seal for the same application and are thus unsuitable for use. The ideal seal would have the axial length of a lip seal with the performance of a mechanical face seal. Attempts at shortening existing mechanical face seals have not been successful due to seal face distortion as seal axial length is reduced. Distortion of the seal face causes seal leakage to increase excessively and thus the seal cannot be used.
Additionally, rotors on existing mechanical face seals normally are positioned against a step in the shaft or the end of a bearing to prevent axial movement of the rotor relative to the shaft. Existing rotors normally also have engagement into the shaft to ensure that the rotor rotates with the shaft. If a mechanical face seal is to be used to replace an existing lip seal, the rotor must be capable of being positioned on a shaft without a step and be capable of being rotated with the shaft without relative axial or radial movement. The rotor must also prevent leakage between the rotor and the shaft.